Are paint tins Hazardous Waste?

I’m frequently asked whether empty containers that have had hazardous substances in them (gloss paints, adhesives, etc) are always Hazardous Waste (Special Waste in Scotland), and if not, when do the containers stop being considered hazardous? The strict answer to this is contained in Example 10 (p.A48) of EA Technical Guide WM2, but the slide below illustrates the basic principles:

De minimisAfter the first question about what the container itself is made of, is whatever you’ve been using only hazardous because of a solvent in it? Consider: If you had to throw away whatever you’ve just painted, or treated, or glued together, would you consider THAT hazardous because of the product you’ve used on it? If you would (for example applying a timber preservative), the container remains hazardous even if its nominally empty and completely dry unless you wash and clean the container to remove all traces of the product from both the inside and outside surfaces. If however it’s just a solvent that’s the issue, you can move onto the final test.

So, how much of the product remains, and what’s the risk of the solvent remaining other than in the very short term? For the first part, WM2 uses the phrase “nominally empty” which is normally accepted to be the same as the old “de minimis rule” – it’s “nominally empty” if less than 1/1000 (0.1% – a common risk threshold) of the original contents remain in the container. The final part is about whether or not the residue is open to the atmosphere so that any solvent remaining in the last 1/1000th can evaporate. So, a nominally empty gloss paint tin with its lid on would still be hazardous waste, but if you remove it, it’s not. The same principle applies to depressurising aerosol cans such as spray markers – left sealed they remain hazardous waste, but open them up (and providing all the other conditions are met), they are no longer hazardous waste.

But – if in doubt, it’s better to err on the side of caution and assume it’s hazardous unless you are certain it’s not!